Both a silicone rubber and a fluorine rubber are rubbers having oil resistance and heat resistance, and these rubbers have been widely employed in various fields. The silicone rubber is excellent in low temperature resistance, a low degree of hardness, and amine resistance, which are properties which is difficult for the fluorine rubber to improve, and furthermore, with respect to processing, the silicone rubber can be applied to a wide variety of processing such as LIM molding.
On the other hand, due to excellent chemical resistance, solvent resistance and heat resistance, the fluorine rubber shows high reliabilities that the silicone rubber can not obtain and has been employed for applications where other materials can not be employed.
Since these two rubbers have a property of supplementing each other, it is expected that a new material is provided if the rubbers can be composed by blending, alloying and the like, and various composites of these two polymers have been studied heretofore.
For example, it is disclosed that a blended material of an iodine containing fluorine elastomer and a vinyl group containing silicone rubber are crosslinked by using a peroxide (for example, see Japanese Unexamined Patent Publication No. 55-50051). Also, a method of blending a fluorine rubber introduced with a double bond and a silicone rubber and conducting co-crosslinking is disclosed (for example, see Japanese Unexamined Patent Publication No. 06-192524). But excellent properties can not be expected since the two polymers are hard to fully disperse finely and uniformly if two kinds of polymers, which are not compatible, are plainly blended and crosslinked
With respect to technology relating to a block or a graft, an elastomer composition which is obtained by dissolving a silicone rubbers in Freon 113 and graft bonding with VdF/HFP is disclosed (for example, see Japanese Unexamined Patent Publication No. 01-240552). But excellent properties can not be expected since a reactive site for the graft is not uniform.
Also, a graft copolymer using tetrafluoroethylene/propylene copolymer for a fluorine rubber is disclosed (for example, see Japanese Unexamined Patent Publication No. 56-28219). But, an excellent vulcanizing property can not be expected since a curing site is an epoxy group, an amino group, an organic acid group or a vinyl group.
Furthermore, a vulcanizing rubber composition in which compatibility of a fluorine rubber and an organopolysiloxane is improved by using an organosiloxane having a particular functional group is disclosed (for example, see Japanese Unexamined Patent Publication No. 04-180930). Although organosiloxane improves compatibility of a fluorine rubber polymer and a silicone, sufficient compatibility can not be expected since the organosiloxane does not contain a component of a fluorine rubber.
The present invention provides a graft or a block polymer in which a fluorine rubber and a silicone rubber are chemically bonded.